This application requests support to continue development of research in the related fields of laryngeal physiology, pathophysiology, and biomechanics. The long-range goals of this experimental work are to understand better both normal and pathological phonation and to contribute to the development of valid, comprehensive and noninvasive clinically feasible methods of representing and measuring the physiology of phonation. The first project involves the simulation of normal and pathological phonation conditions by quantitatively manipulating parameters such as vocal fold tension and the symmetry of the glottis in the Finite Element Analysis (FEA) model;EGG and PGG output along with inner stress will be simulated. Inner stress is a valuable measurement capable of providing valuable insight into trauma generation and deterioration, as well as prevention of voice misuse. In the second project, high-speed imaging will measure mucosal wave motion (including amplitude and phase difference) in excised larynges. The effects of vocal fold adduction, abduction, and tension, as well as pathological conditions on mucosal wave motion will be investigated. The third project will further develop spatiotemporal analysis of high-speed imaging data. Temporal instability and spatial variance will be measured using spatial correlation analysis and global entropy. Spatiotemporal analysis of high-speed imaging data will be further applied to study vibratory characteristics of vocal folds under pathological conditions. The relationship between mucosal wave analysis and spatiotemporal analysis will be investigated. The fourth project will examine the measurement of vocal fold inner stress and its distribution in normal and pathological conditions based on the surface dynamics of the vocal fold seen in high-speed video. The fifth project will engineer a method to estimate biomechanical parameters of vocal folds in normal and pathological conditions. Utilizing Genetic Algorithm (GA) from the experimentally measured time series, such high-speed imaging, EGG, PGG, and acoustics, we can estimate both the stiffness and mass changes due to vocal fold pathology. This research will produce direct measurements taken from the excised larynx model, which can then be compared to measurements using developed non-invasive methodologies. These results will serve in both establishing validity and calibrating the noninvasive measurements. Developed methods could potentially serve as a non-invasive diagnostic approach for vocal fold disorders.